1. Digital Electronics, Software and Hardware
K. A. Connor
Mobile Studio Project
Center for Mobile Hands-On STEM
LESA Engineering Research Center
ECSE Department
Rensselaer Polytechnic Institute

2. Outline Digital Static I/O with Analog Discovery
Photocell Light Sensor Circuit
TTL Gates
PWM from Digital Output

3. Static I/O 16 Channels Configuration Right Click Channel
Input
Output
Right Click Channel
LED for Output
Switch for Input
Config – Bit I/O

4. Photocell Sensor
A Photocell is a resistor whose value reduces with increasing light levels
Photocell
Voltage Divider
Fixed R Meas.
Photocell Meas.
Fixed Resistor chosen to achieve maximum range of measured voltages. Very common sensor for Arduinos and other processors

5. TTL Gates
Transistor–transistor logic (TTL) is a class of digital circuits built from bipolar junction transistors (BJT) and resistors.
TTL NAND Gate
Truth Table Experiment

6. PWM from Digital Output
Previously used PWM from Analog Discovery function generator (W1 or W2)
All 16 Digital I/O Channels can also provide a PWM signal
Many more channels and
Can be controlled by and a key part of a fully digital system and, thus, generally more flexibly, if not necessarily more easily, programmed.

7. Functional Blocks Generic Circuit System
Source
Transfer Function
Load
Generic Circuit System
Source (voltage plus resistance, as in Thevenin Equivalent)
Intermediate Circuit (characterized by a transfer function … filter, amplifier, etc.)
Load (resistance, capacitance, inductance or combination)
Voltage divider for Zin and Zout

8. Adding Functional Blocks
Adding Functional Blocks to a Circuit can Radically Change What the Circuit Does
Potential Issues
Check input and output impedances to be sure independent functions work together
Check input and output voltage, current, power to be sure that they are adequate
Voltage Divider Video 6.1 (Designing Circuits from Functional Blocks)

9. Ready for Next Experiment
All systems in place
Sensor (Photocell)
Processor (Analog Discovery)
Actuator (LED)
Model for other systems